TEM AND DLTS INVESTIGATIONS OF THE ELECTRICAL-ACTIVITY OF NEAR-COINCIDENCE GRAIN-BOUNDARIES IN GERMANIUM

The electronic defect states of near SIGMA9, SIGMA17, and SIGMA41 tilt grain boundaries (GBs) in germanium have been determined by means of deep-level-transient spectroscopy (DLTS). The results indicate energy levels E(c) - (0.56 +/- 0.02) eV and E(c) - (0.38 +/- 0.02) eV for the SIGMA9, SIGMA17, and the SIGMA41 GBs, respectively. The structure of these GBs has been further studied by transmission electron microscopy (TEM). Because of a small twist component of the misorientation in th e SIGMA9 and SIGMA17 bicrystal, GB dislocations have (almost-equal-to 3 x 10(16) m-2) jogs. These jogs are studied by HREM and evidently cre ate dangling bonds which are considered to be at the origin of the ele ctrical activity of the SIGMA9 and SIGMA17 GB. No structural feature h as been found which may create jogs or dangling bonds in the small ang le SIGMA41 GB. The results are published fully in phys. stat. sol. (b) 166, 347 (1991) and 170, 403 (1992).